Power & Motor Control Center
The most basic type of AC motor control, for example,involves turning the motor on and off. This is often accomplished using a motor starter made up of a contactor and an overload relay.
The contactor’s contacts are closed to start the motor and opened to stop the motor. This is accomplished electro-mechanically using start and stop push buttons or other pilot devices wired to control the contactor.
The overload relay protects the motor by disconnecting power to the motor when an overload condition exists. Although the overload relay provides protection from overloads, it does not provide short-circuit protection for the wiring supplying power to the motor. For this reason, a circuit breaker or fuses are also used.
Typically one motor starter controls one motor. When only a few geographically dispersed AC motors are used, the circuit protection and control components may be located in a panel near the motor.
In many commercial and industrial applications, quite a few electric motors are required, and it is often desirable to control some or all of the motors from a central location. The apparatus designed for this function is the motor control center (MCC).